Google ranks all websites together in one pot. It does not separate out WordPress sites for a special index. That means that WordPress SEO is, at its base, no different than SEO for any other website.
As with any other website, you need both on-page and off-site SEO – both proper coding and content and good links and social signals.
As with any other website, it’s not how good your SEO is, it’s how much better (or worse) it is compared to the competition.
As with any other website, the title tag is prime real estate, as are the h tags and the bold tags.
As with any other website, the speed of loading and the mobile compatibility are crucial.
As with any other website, you need to know which search terms (keywords) people are searching for and, more importantly, which ones convert.
What’s so special about WordPress SEO
What’s different is that WordPress is a content management (CMS), so there are very specific ways to control some aspects that affect SEO.